The invention is a water table such as those used for plasma cutting that can change the water level as well as provide an automated cleaning system for the water.
The invention relates generally to water tables used for cutting metal but more particularly to self-cleaning water tables comprised of means to raise and lower the water level.
Plasma cutting releases dangerous gas fumes and the metals being cut also release small airborne particles that, when mixed with the plasma gases, can foul the surrounding air. Moreover, plasma cutting is very noisy, very bright and very hot. For all these reasons, underwater cutting has been used for many years for that type of metal cutting. Although it has solved a number of problems, underwater cutting also brought about its own set of inconveniences. For example, the metal sheets can become slippery when left underwater, which can be hazardous for workers who have to handle them. For this and other reasons discussed in patent application 3,792,846 by Geffert, water tables having means to raise or lower water level have been developed and some of these patents, including the above cited, include means to clean the cutting residues which would have previously been released into the air. The preferred method of raising or lowering the water level consists of the use of compressed air to push water out of a small tank and into the larger water table containment. This method requires a smaller tank to hold surplus water and necessitates the use of compressors to push air into the smaller tank in order to evacuate water out of that tank and into the water table. The larger the size of the water table, the greater the needs for huge compressors, large air tanks and all the attendant costs involved in that extra hardware. Example of that method can be found in patent 4,162,060 by Anderson.
Furthermore, using air to move water creates a lot of turbulence which causes particles in the water to remain suspended longer. Polluted water tends to reduce the usable life of the consumable parts of the cutting torch. Methods currently in use, such as those described in patents 3,792,846, 4,453,702 and 4,867,797 will either handle the cleaning of large debris very well but not small particles or vice versa but not both. Patent 4,162,060 for example doesn""t handle the disposal of slag very well.
There are a number of other patents relating to water displacements and methods of cleaning the water but none include all of the novel features of this instant invention.
The purpose of this invention is to provide a practical and economical alternative to existing water tables used for cutting.
It is an object of this invention to provide a practical means of raising and lowering the water in the water table which reduces the agitation of the water so as to reduce the movement of suspended particles since no air or other gases are used directly upon the water in order to push it (as per patent 4,162,060 by Anderson).
It is another object of the invention to provide means to create a small bi-directional current in the water to move the suspended particles as well as the already deposited particles and small cutting residues (generally referred to as xe2x80x9cslagxe2x80x9d)toward the edges of the water table.
It is yet another object of the invention to provide a means to keep the water as clean as possible to prolong the life of the consumable parts of the cutting torch as well as keeping the parts being cut, cleaner.
It is a further object of the invention to provide an efficient conveyor means to remove the slag that has accumulated around the bottom periphery of the water table.
To accomplish that, this invention is comprised of a movable platform that can be raised or lowered, thus physically reducing the interior volume of the water table. Having less volume, the water is displaced in a manner which elevates its level inside the water table. This method of raising and lowering of the water level in the water table results in minimal turbulence and does not overly agitate suspended particles thus keeping the water cleaner.
Furthermore, because of the slanted slope of the movable platform, raising it creates currents in the water which direct suspended particles, mostly found above the sloped floor part of the water table, toward the edges of the water table, there, they fall down onto a continuous loop conveyor that takes them out of the water table.
Other advantages will become evident upon reading the description.